Air admission apparatus for water control gate

ABSTRACT

An apparatus is disclosed for admitting atmospheric air to a bounded volume of air on a downstream side of a crest gate where the bounded volume is defined by the gate and a curtain of water spilling over the gate. The apparatus comprises a plurality of rigid conduits secured to the gate and sized sufficient to have a first opening in communication with atmospheric air and second opening in communication with the bounded volume of air. The rigid conduits are secured to the gate and spaced along the length of the gate to divide the curtain of water flowing over the gate into a plurality of separate water currents. Permitting communication between atmospheric air and the bounded volume of air, the rigid conduits act to abate damaging vibration to the gate caused by the flow of water over the crest of the gate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to water control gates such as crest gates. In particular, this invention relates to apparatus for admitting air to the downstream side of the gate for abating vibration caused by water spilling over the top of the gate.

2. Description of the Prior Art

Water control gates, such as crest gates, for controlling the flow of water through a waterway are well known. Examples of water control gates are found in U.S. Pat. No. 2,621,484 to Jermar dated Dec. 16, 1952; U.S. Pat. No. 2,073,956 to Becher dated Mar. 16, 1937 and U.S. Pat. No. 2,077,203 to Becher dated Apr. 13, 1937. Such gates have a bottom portion which are pivotally mounted to the floor of the waterway with the gate extending between sidewalls of the waterway. The gate is pivoted between a closed position with the gate generally vertical and an open position with the gate pivoted toward the downstream waterflow. Generally, such gates are used to maintain a constant water level on the upstream side of the gate.

When in any given pivotal position, a curtain of water flows over the top of the gate. When a thin curtain of water is passing over the gate, this curtain will vibrate as it falls over the gate. The vibration of this curtain causes low frequency sound waves which can be obnoxious to residents in the surrounding vicinity. The longer the gate, the more obnoxious the sound. When the amount of water flowing over the gate is increased, the curtain of water thickens. The thick curtain of water flowing over the gate cooperates with the gate to define a bounded air chamber on the downstream side of the gate. When pressure differentials occur between atmospheric air and the bounded air chamber, damaging vibrations can occur to the gate. This phenomena is recognized in U.S. Pat. No. 2,118,535 to Betts dated May 24, 1938. To prevent these damaging vibrations, prior art water control gates, such as crest gates, were provided with air manifolds built into the sidewall structures of the gate. The air manifolds included piping which permitted air flow communication between the downstream side of the gate and atmospheric air. The sidewall mounted air admission apparatus is effective for water control gates which are mounted on top of dams. An example of such may be found in FIG. 1 of the aforementined U.S. Pat. No. 2,621,484. However, such sidewall mounted manifolds are not operable for water control gates which are mounted on the floor of a waterway. In such cases, there is a variable downstream water level on the downstream side of the gate. The existence of this water level and the stroke of the gate prevent the situation of the manifolds in the sidewalls since there is no practical position with which to admit air to the downstream side of the gate.

It is a general object of the present invention to provide an apparatus for admitting air to a bounded air chamber on the downstream side of a water control gate.

Another object of the present invention is to provide an apparatus for admitting air to the bound air chamber on the downstream of a water control gate which is operable independent of the water level on the downstream side of the gate.

Still another object of the present invention is to provide an apparatus for admitting air to the air chamber on the downstream side of a water control gate which also functions to divide the current of water flowing over the gate into a plurality of smaller curtains and thereby abate sound vibrations.

SUMMARY OF THE INVENTION

According to a preferred embodiment of the present invention, there is provided a water control gate comprising a gate received within a waterway. A bottom portion of the gate is pivotally secured to the floor of the waterway and the gate extends between sidewalls of the waterway. Means are provided for moving the gate between a maximum closed position and an open position. In the maximum closed position, the gate is in a generally vertical position and maintains a water level upstream of the gate at a predetermined desired water level. The gate is rotatable to a plurality of open positions with the gate rotated toward the downstream side of the waterway. Water spilling over the top edge of the gate presents a water current which cooperates with the gate to define a bounded volume of air on the downstream of the gate.

A plurality of air admission pipes are secured to the gate and sized sufficient to extend through the water current with the pipes having a first opening in communication with atmospheric air and a second opening in communication with the bounded volume of air. The plurality of air admission pipes are secured to the gate and divide the current of water flowing over the gate into a plurality of separate water curtains--each shorter than the total length of the gate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of a water control gate within a waterway shown partially in section to expose the pivotal connections between the gate and the floor of the waterway;

FIG. 2 is a view of a gate taken along lines II--II of FIG. 1; and

FIG. 3 is a view of the gate taken along lines III--III of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, a water control gate 10, more specifically a crest gate, is shown within a waterway. The waterway comprises a floor 11 and two parallel spaced apart sidewalls 12 and 13. The crest gate 10 is sized to be received within the waterway extending between the sidewalls 12 and 13 with a bottom portion of the gate 10 pivotally secured to the floor 11 of the waterway. The gate 10 comprises a torque tube 14 along the bottom edge of the gate which is pivotally secured to the floor 11 of the waterway by means of a plurality of pivotal connections 15. The gate 10 includes a skin plate 16 which extends radially from the torque tube 14 and is provided with a radial dimension sufficient to retain water upstream of the gate at a desired water level 17. A plurality of radially extending reinforcing ribs 18 are laterally spaced along the skin plate 16 and welded thereto to reinforce the skin plate. Means 19 are provided for pivotally rotating the torque tube 14 with resulting rotation of the skin plate 16.

Referring now to FIG. 2, the crest gate 10 is shown in a closed position with the gate 10 generally vertical and maintaining a water level 17 upstream of the gate at a desired level. The gate is provided with a downstream projecting flange 20 at the crest 21 of the gate. As can be seen in FIG. 2, since the crest gate is positioned on the floor of a waterway, a water level 22 develops on the downstream side of the gate. When the water flow upstream of the gate increases, the gate is pivoted toward the downstream side of the gate to permit a greater amount of the water to flow over the gate 10 and thereby maintain a desired level 17 of water upstream of the gate. As shown in FIG. 2, water 23 flowing over the gate cooperates with the gate 10 to define a bounded volume of air 24 on the downstream side of the gate.

As shown in both FIGS. 1 and 2, a plurality of air admission pipes 25 are secured to the gate 10 for permitting air flow communication between atmospheric air and the bounded volume of air 24 on the downstream side of the gate. The air admission pipes 25 comprise structural steel tubing which is square in cross section with each tube 25 secured to the gate 10 by welding the tube 25 to both the skin plate 16 of the gate 10 and a reinforcing rib 18. The tubes 25 are secured to the gate 10 to be radial to the torque tube 14 with the tubes being of sufficient length to extend through the curtain of water 23 flowing over the top of the gate. The tubes 25 have a first opening 26 in communication with atmospheric air and a second opening 27 in communication with the bounded volume of air 24 on the downstream side of the gate 10.

As shown in FIGS. 1 and 3, a plurality of air admission tubes 25 are spaced along the gate 10 to divide the curtain 23 of water flowing over the gate 10 into a plurality of smaller curtains. Each tube 25 is secured to the gate 10 so that a diagonal of the cross section of the tube 25 is normal to the flow of water over the gate (as shown in FIG. 3). In such an alignment, the tube 25 presents its greatest cross-sectional dimension to the flow of water over the gate 10 thereby increasing the effectiveness of the tubes 25 in interrupting the curtain of water into a plurality of smaller curtains.

In a specific example where a crest gate 10 is mounted on the floor 11 of a waterway to maintain water upstream of the gate at a water level 17 of six feet, a crest gate 10 will typically be maintained in its maximum closed position until the curtain 23 of water flowing over the gate exceeds six inches, at which point the gate 10 will be lowered to maintain the upstream water level at six feet. When the level of water upstream of the gate exceeds the desired water level by twelve inches, the gate is rotated toward the downstream with the gate resting on the floor 11 of the waterway. As shown in FIG. 2, the floor 11 is recessed, as shown by the broken line 30, to receive the gate 10 as shown in the fully open position by the phantom lines 31. For such an example, a preferred air admission tube 25 will be approximately sixty-five inches in length and be secured to the gate 10 so that approximately twenty-four inches of the tube 25 extends above the top edge, or crest 21, of the gate. In such an example, the air admission tubes 25 operate to permit air flow communication between atmospheric air and the bounded volume of air 24 downstream of the gate until the gate is rotated to a position with the skin plate 16 of the gate and a plane radially horizontal to the torque tube 14 defining a lesser included angle of approximately 60 degrees at which point the top of the air admission tube will be submerged in water and no communication with atmospheric air is permitted. However, this does not present a problem since at such a rotation, there is no bounded volume of air on the downstream side of the gate. Preferably, such a tube 25 will have a cross section of six inches by six inches.

From the foregoing detailed description of the present invention, it has been shown how the objects of the present invention have been attained in a preferred manner. However, modifications and equivalents of the disclosed concepts, such as readily occur to those skilled in the art, are intended to be included in the scope of this invention. Thus, the scope of the invention is intended to be limited only by the scope of the claims such as are, or may hereafter be, appended hereto. 

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
 1. A water control gate comprising a gate having a tube member with a plate member extending from said tube member and sized to be received within a waterway with means pivotally securing said tube member to a floor of said waterway and said plate member extending between sidewalls of said waterway; said gate further having a plurality of radially extending reinforcing ribs laterally spaced along a downstream surface of said plate member;means for pivotally moving said gate between a maximum closed position and a plurality of open positions with said gate pivoted toward a downstream side of said waterway when rotated toward said open positions; a rigid conduit secured to a downstream side of said gate for movement therewith and extending generally radially from the axis of rotation of said gate; said conduit sized sufficient to present a first opening in communication with atmospheric air and a second opening in communication with a bounded volume of air defined by said downstream radial surface of said gate and a water curtain spilling over said gate.
 2. A water control gate according to claim 1 wherein said water control gate is provided with a plurality of said rigid conduits spaced along said gate with said conduits dividing said water curtain into a plurality of separate water curtains.
 3. A water control gate according to claim 2 wherein said conduits present a maximum cross-sectional dimension normal to the flow of water over said gate. 